- Joined
- Apr 28, 2015
- Messages
- 173
Air speed is better on the stock RH10 than I thought it would be. 9whp is a lot going into that 20cfm. Which is to the point that it is not all CFM, I suspect the larger valve size removes a bottleneck.
RH4 To Narley Port Conversion Tubes
- Thread starter maaseyracer
- Start date
Air speed is better on the stock RH10 than I thought it would be. 9whp is a lot going into that 20cfm. Which is to the point that it is not all CFM, I suspect the larger valve size removes a bottleneck.
- Joined
- Nov 26, 2009
- Messages
- 3,202
If it was ported then its larger than 30mm now. Can you say how much larger it is and where?
Yes porting is very important. I sent some modified Axtell port specs to a 500 cc racer in the UK and he found a 7 hp increase (same size valves).
Brian's 500 (pre 1950 class)
Last edited:
Fast Eddie
VIP MEMBER
- Joined
- Oct 4, 2013
- Messages
- 21,548
Still 30mm Jim (like I clearly stated). Work was done around the valve throat only.If it was ported then its larger than 30mm now. Can you say how much larger it is and where?
Yes porting is very important. I sent some modified Axtell port specs to a 500 cc racer in the UK and he found a 7 hp increase (same size valves).
Brian's 500
Last edited:
- Joined
- Jun 30, 2012
- Messages
- 13,918
As far as speed is concerned, weight distribution can be more important than horsepower. If the front feels light, it will deter you from accelerating earlier when in corners.If it was ported then its larger than 30mm now. Can you say how much larger it is and where?
Yes porting is very important. I sent some modified Axtell port specs to a 500 cc racer in the UK and he found a 7 hp increase (same size valves).
Brian's 500 (pre 1950 class)
- Joined
- Apr 28, 2015
- Messages
- 173
Been working on these now for a while now and I think I am where I want to be with these. 3D printing the tube to get the size consistent proved to be a massive headache and hit the current limits of the technology. The success I had with these tubes required hand porting them to dimension which while very effective and easy for a one off, would have made these things very expensive to produce. Moving to just a floor we are able to take advantage of what is working in our favor with the larger ports.
A somewhat expected issue added another layer of complexity with these, which is getting the spacing with the frame figured out. I wanted to make sure with this design that carburetors did not become any more limited than they already are. With carbs like the Keihin CRS that I am running they just barely fit and I do not want to run into any issues with that. Port fit is really good and consistent with samples and the initial run I am sending over to Jim Schmidt, he will be taking this one over like the exhaust. These will be sold with a special gasket set and may require a sealant as well and I will update on the specifics of the sealant hopefully later this week.
While these are for the 32mm port heads I do have a version of this I am working on for a 30mm Norton head, which I have sent off to get samples along with some similar floors for other bikes. If all looks right with the 30mm floors they should follow be ready fairly soon.
If you want a set connect with Jim I imagine he will have them posted in the coming weeks.
A somewhat expected issue added another layer of complexity with these, which is getting the spacing with the frame figured out. I wanted to make sure with this design that carburetors did not become any more limited than they already are. With carbs like the Keihin CRS that I am running they just barely fit and I do not want to run into any issues with that. Port fit is really good and consistent with samples and the initial run I am sending over to Jim Schmidt, he will be taking this one over like the exhaust. These will be sold with a special gasket set and may require a sealant as well and I will update on the specifics of the sealant hopefully later this week.
While these are for the 32mm port heads I do have a version of this I am working on for a 30mm Norton head, which I have sent off to get samples along with some similar floors for other bikes. If all looks right with the 30mm floors they should follow be ready fairly soon.
If you want a set connect with Jim I imagine he will have them posted in the coming weeks.
Last edited:
- Joined
- Mar 6, 2010
- Messages
- 19
Just wondering if a recess has to be machined in the head to fit them in order to clear the frame (carbs)? btw, I have a Combat base and head will they fit this one (head)?Been working on these now for a while now and I think I am where I want to be with these. 3D printing the tube to get the size consistent proved to be a massive headache and hit the current limits of the technology. The success I had with these tubes required hand porting them to dimension which while very effective and easy for a one off, would have made these things very expensive to produce. Moving to just a floor we are able to take advantage of what is working in our favor with the larger ports.
A somewhat expected issue added another layer of complexity with these, which is getting the spacing with the frame figured out. I wanted to make sure with this design that carburetors did not become any more limited than they already are. With carbs like the Keihin CRS that I am running they just barely fit and I do not want to run into any issues with that. Port fit is really good and consistent with samples and the initial run I am sending over to Jim Schmidt, he will be taking this one over like the exhaust. These will be sold with a special gasket set and will most likely require a sealant as well and I will update on the specifics of the sealant hopefully later this week.
While these are for the 32mm port heads I do have a version of this I am working on for a 30mm Norton head, which I have sent off to get samples along with some similar floors for other bikes. If all looks right with the 30mm floors they should follow be ready fairly soon.
If you want a set connect with Jim I imagine he will have them posted in the coming weeks.
- Joined
- Apr 28, 2015
- Messages
- 173
No machining required. Drop in and go.
- Joined
- Nov 26, 2009
- Messages
- 3,202
If you look closely you can see that there is a teflon gasket surrounding the metal ring. The teflon stands proud of the ring a few thou to create a perfect seal to prevent vacuum leaks. The white teflon seal in the photo is a hand cut prototype and not a perfect fit - the perfect fit will happen when the teflon is sent out to be waterjet cut. These port floors started out with the Narley port floor and was then combined with the ring for easy installation (following the exhaust port floor idea).
Here's a view from the combustion chamber side. There is a little downward pressure exerted at the tip for sequrity when the ring is tightened down by the manifold as shown below. The raised intake port floor gives a better more gradual curve leading up to the valve seat for increased velocity
Below is a side view overlay showing how the port floor improves the curve and flow leading up to the intake valve.
Last edited:
- Joined
- Oct 28, 2014
- Messages
- 1,987
Will there be a 750 version?